1. Field of the Invention.
This invention relates in general to CMOS. transmitting and receiving devices, and more specifically, to CMOS devices that use low voltage logic swings and transmission line drivers to increase the amount of data per unit time on the communications link.
2. Description of Related Art.
Complementary Metal Oxide Semiconductor (CMOS) transmitters and receivers are widely used in the industry to transport data. The low power requirements and low device costs make CMOS devices desirable for most applications, such as personal computer (PC) communications, spacecraft data storage and transmission, and mainframe computer uses. As technology has advanced, the conductive paths inside of semiconductor devices has been reduced to sub-micron widths in order to increase the on-chip processing speeds. As line widths decrease, capacitive coupling and crosstalk interfere with the device's ability to output signals strong enough to communicate with other devices. The disparity between on-chip processing speeds and inter-chip communication speeds becomes increasingly troublesome as CMOS technology scales down into the sub-micron region. Other technologies, such as Gallium Arsenide (GaAs), and other logic families, such as Emitter Coupled Logic (ECL), use lower voltage swings and transmission line drivers and receivers, thereby reducing the interference problem of small on-chip line widths and allowing higher speed data transmission. However, GaAs and ECL require more power than CMOS devices, therefore making these alternative devices unsuitable where low power consumption is an important design criteria.
It can be seen then that there is a need for a CMOS device that uses low voltage swings which allows for a higher speed CMOS transmission link. It can also be seen that there is a need for a CMOS device that uses transmission line effects for more efficient transmission of data. Further, there is a need for a CMOS device that can interface with either a CMOS or ECL transmitter/receiver.